1 mad as a fish
2 mad as they come
3 mad as hops
4 mad as a hatter
5 mad as a March hare
6 mad as a pink balloon
7 mad as snow
8 mad as fudge
9 mad as the Dickens
10 mad as wet hen
11 mad as honey
12 mad as Napoleon
13 mad as cheese
14 mad as skipload of squirrels
15 mad as a brush
16 mad as a magpie
17 mad as a box of frogs

Note, this is 'mad' as in lunatic, not as in the American (mad as a hornet) or Australian (mad as a cut snake) sense of anger. See also crazy as hell / a loon / a fox / a soup sandwich / a jaybird.